関連ワード:  sql query check if column is null    sql query check if field is null    sql query to check if column is empty    sql query to check if any column is null    sql query to check if column is not null    sql query to check if field is empty    sql query to check if column is null or empty    sql query to check if column is not empty    sql query to check if column is not null or empty    sql query to check if column value is not null